1. Field of the Invention
The present invention relates to a method of printing a strip-like film in a form-fill-seal packaging machine and enclosing commodities into packaging bags while forming the strip-like film onto the packaging bags and a form-fill-seal packaging machine using the printing method.
2. Description of the Related Art
As disclosed in, for example, Japanese Unexamined Patent Publication No. 1362/1991, there is known a FORM-FILL-SEAL packaging machine in which a strip-like film is unreeled from a roll. While running the film along a running path, the film is curved into a cylindrical shape at a downstream end portion of the running path. Overlapped end edge portions and lower end portions of the cylindrical film are respectively bonded and sealed. Thereafter, commodities are supplied. Afterwards, upper end portions of the cylindrical film are similarly welded, sealed and separated by cutting whereby packaging bags enclosed with the commodities are successively formed.
In this case, as disclosed in, for example, Japanese Unexamined Utility Model No. 32611/1984 or Japanese Unexamined Patent Publication No. 127533/1994, a printing device such as a printer is arranged on the running path of the film and predetermined information such as the manufacturing date, manufacturing number, etc. is printed on the film before the film is introduced into the downstream end portion and is formed into bags. In such a case, there are form-fill-seal packaging machines of a type continuously running the film and a type intermittently running the film. Further, there are printing systems, which are known, with respect to the film in accordance with the types of the form-fill-seal packaging machines and a continuous printing type printing on the film while rotating a printing unit of a printing device in synchronism with the running of the film and an intermittent printing system printing the film in a period of time during which the film is intermittently stopped.
According to the continuous printing system, the strip-like film can be run continuously and therefore, the processing capacity of the form-fill-seal packaging machine is increased. However, a complicated synchronizing mechanism must be adopted at the printing unit and it is also necessary to reset timings of the rotational movement of the printing unit and the printing operation in accordance with the change of the length of the bag or the location of printing.
According to the intermittent printing system, the constitution as well as the control of the printing timing are comparatively simplified and therefore, the printing device per se is inexpensive. However, the form-fill-seal packaging machine is inferior in view of its processing capacity since the strip-like film must be stopped at every printing.